This present invention relates generally to manufacturing objects. More particularly, the invention relates to a method and structure for fabricating a release structure for spatial light modulators. Merely by way of example, the invention has been applied to the formation of a release structure to facilitate bonding of mirror devices onto a substrate. The method and device can be applied to spatial light modulators as well as other devices, for example, micro-electromechanical sensors, detectors, and displays.
Micro-electromechanical systems (MEMS) are used in a number of application areas. For example, MEMS have been used in micro-mirror arrays, sensors, and actuators. In some of these applications, a suspended member is supported by a flexible hinge attached to a stationary portion of the micro-mirror array. Flexibly attached to the hinge, the suspended member is attracted to an electrode upon application of an electrical force and restored to an original position by a restoring force. In this manner, the array of micro-mirrors can be tilted in relation to a light source. In some applications, it is beneficial to have the hinge located beneath the micro-mirror surface in a hidden position, enabling the fill factor of the array to be increased. As the fill factor of the micro-mirror array is increased, the potential quality of two-dimensional images created by optical systems using the array is improved.
As merely an example, some conventional MEMS have utilized various micro-mirror designs, such as micro-mirrors mounted on flexible pedestals coupled to the backside of the micro-mirror surface. In some of these designs, the flexible pedestals extending from the mirror substrate are bonded to a control substrate using a wafer bonding process. However, in these designs, the reliability and repeatability of the process of bonding the flexible posts to the control substrate may be reduced due to the small surface areas joined during the bonding process. Thus, there is a need in the art for methods and apparatus for fabricating a release structure to facilitate bonding of mirror devices onto a substrate.